Semiconductor package structure having first and second guard ring regions of different conductivity types and method for forming the same

ABSTRACT

A method for forming a semiconductor package structure is provided. The method for forming a semiconductor package structure includes providing a substrate, wherein the substrate has a front side and a back side, forming a first guard ring doped region and a second guard ring doped region in the substrate, wherein the first guard ring doped region and the second guard ring doped region have different conductive types, forming a trench through the substrate from a back side of the substrate, conformally forming an insulating layer lining the back side of the substrate, a bottom surface and sidewalls of the trench, removing a portion of the insulating layer on the back side of the substrate to form a through via, and forming a conductive material in the through via, wherein a through silicon via (TSV) interconnect structure is formed by the insulating layer and the conductive material.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of U.S. patent application Ser. No.14/601,440, filed on Jan. 21, 2015, entitled “SEMICONDUCTOR PACKAGESTRUCTURE AND METHOD FOR FORMING THE SAME”, now U.S. Pat. No. 9,543,232,the entirety of which is incorporated by reference herein.

FIELD OF THE INVENTION

The present invention relates to a semiconductor package structure, andin particular relates to a semiconductor package structure with athrough silicon via (TSV) interconnect structure.

DESCRIPTION OF THE RELATED ART

In electronic engineering, a through silicon via (TSV) is a verticalelectrical connection which passes completely through a silicon wafer ordie. A TSV is formed by high-performance techniques, when compared toalternatives such as package-on-package. A TSV is used to createthree-dimensional (3D) semiconductor packages and 3D integratedcircuits. The density of the via of a TSV is substantially higher thanthe alternatives as the length of connections thereby are shorter.

An insulating liner of the conventional TSV serves as a capacitorbetween the silicon wafer and the TSV via plug. In high-speedapplications (e.g. RF applications), the electrical impedance of aconventional TSV is reduced due to the insulating liner. When high speedcircuits (e.g. digital circuits) transmit signals, the signals arecoupled from the high speed circuits to other nodes such as the TSVs ofanalog circuits. Thus, noise coupling occurs and interferes with theother sensitive circuits (e.g. analog circuits), affecting the overallperformance of the semiconductor package, which requires a high clockrate and analog precision.

Thus, a novel noise coupling suppression structure for a semiconductorpackage with a TSV interconnect is desirable.

BRIEF SUMMARY OF THE INVENTION

A detailed description is given in the following embodiments withreference to the accompanying drawings.

In an embodiment, a method for forming a semiconductor package structureis provided. The method for forming a semiconductor package structureincludes providing a substrate, wherein the substrate has a front sideand a back side, forming a first guard ring doped region and a secondguard ring doped region in the substrate, wherein the first guard ringdoped region and the second guard ring doped region have differentconductive types, forming a trench through the substrate from a backside of the substrate, conformally forming an insulating layer liningthe back side of the substrate, a bottom surface and sidewalls of thetrench, removing a portion of the insulating layer on the back side ofthe substrate to form a through via, and forming a conductive materialin the through via, wherein a through silicon via (TSV) interconnectstructure is formed by the insulating layer and the conductive material.

In another embodiment, a method for forming a semiconductor packagestructure is provided. The method includes providing a substrate,wherein the substrate has a front side and a back side; forming a firstguard ring doped region and a second guard ring doped region in thesubstrate; forming a trench through the substrate from a back side ofthe substrate; conformally forming an insulating layer lining the backside of the substrate, a bottom surface and sidewalls of the trench;removing a portion of the insulating layer on the back side of thesubstrate to form a through via; and forming a conductive material inthe through via, wherein a through silicon via (TSV) interconnectstructure is formed by the insulating layer and the conductive material,wherein the first guard ring doped region and a second guard ring dopedregion are adjacent to the through silicon via (TSV) interconnectstructure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention can be more fully understood by reading thesubsequent detailed description and examples with references made to theaccompanying drawings, wherein:

FIG. 1 shows a cross-sectional representation of a semiconductor packagestructure, in accordance with some embodiments of the disclosure.

FIGS. 2A-2D show cross-sectional representations of various stages offorming a semiconductor package structure, in accordance with someembodiments of the disclosure.

FIG. 3 shows a cross-sectional representation of a semiconductor packagestructure, in accordance with some embodiments of the disclosure.

FIG. 4 shows a cross-sectional representation of a semiconductor packagestructure, in accordance with some embodiments of the disclosure.

DETAILED DESCRIPTION OF THE INVENTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

Some variations of the embodiments are described. Throughout the variousviews and illustrative embodiments, like reference numbers are used todesignate like elements. It is understood that additional operations canbe provided before, during, and after the method, and some of theoperations described can be replaced or eliminated for other embodimentsof the method.

FIG. 1 shows a cross-sectional representation of a semiconductor packagestructure 100 which is a noise coupling suppression structure, inaccordance with some embodiments of the disclosure. The semiconductorpackage structure includes a substrate 200. The substrate 200 has afront side 201 and a back side 203 opposite to the front side 201. Insome embodiments, the substrate 200 may be made of silicon or othersemiconductor materials. Alternatively or additionally, the substrate200 may include other elementary semiconductor materials such asgermanium. In some embodiments, the substrate 200 is made of a compoundsemiconductor such as silicon carbide, gallium arsenic, indium arsenide,or indium phosphide. In some embodiments, the substrate 200 is made ofan alloy semiconductor such as silicon germanium, silicon germaniumcarbide, gallium arsenic phosphide, or gallium indium phosphide. In someembodiments, the substrate 200 includes an epitaxial layer. For example,the substrate 200 has an epitaxial layer overlying a bulk semiconductor.

An integrated circuit device 220, such as a transistor, is formed on thefront side 201 of the substrate 200. Isolation structures 205 are formedin the substrate 200 and are used to isolate the integrated circuitdevice 220 with other devices (not shown).

A through silicon via (TSV) interconnect structure 230 is formed throughthe substrate 200, and it is extended from the front side 201 of thesubstrate 200 to the back side 203 of the substrate 200. TSV structure230 includes an insulating layer 232 and a conductive material 234. Insome other embodiments, a diffusion barrier layer (not shown) is formedbetween the insulating layer 232 and the conductive material 234.

The insulating layer 232 is made of an insulating material, such asoxides or nitrides. The insulating layer 232 may be formed by using aplasma enhanced chemical vapor deposition (PECVD) process or anotherapplicable process. In some embodiments, the conductive material 234 ismade of copper, copper alloy, aluminum, aluminum alloys, or combinationsthereof. In some embodiments, the conductive material 234 is formed byplating.

A conductive bump 236 is formed on the conductive material 234 and onthe back side 203 of the substrate 200. The conductive bump 236 is madeof conductive materials, such as copper, copper alloy, aluminum,aluminum alloys, or combinations thereof.

A poly pattern 238 is formed on the conductive material 234 and on thefront side 201 of the substrate 200. The poly pattern 238 is used toserves as an etching stop layer

An interconnect structure 252 is formed on the substrate 200. In someembodiments, the interconnect structure 252 includes contact plugs andconductive features. Conductive features are embedded in an inter-metaldielectric (IMD) layer 250. In some embodiments, the IMD layer 250 ismade of silicon oxide. In some embodiments, the IMD layer 250 includesmultiple dielectric layers of dielectric materials. The interconnectstructure 252 shown is merely for illustrative purposes. Theinterconnect structure 252 may include other configurations and mayinclude one or more conductive lines and via layers.

At least two guard ring doped regions 242 and 244 are formed adjacent tothe TSV structure 230. As shown in FIG. 1, a pair of first guard ringdoped regions 242 are formed in the substrate 200 and adjacent to theTSV structure 230. A pair of second guard ring doped regions 244 areformed adjacent to the first guard ring doped regions 242. The first andsecond guard ring doped regions 242 and 244 are coupled to a groundterminal GND. Therefore, the noise coupling from the substrate 200 orthe TSV structure 230 are transmitted to the first and second guard ringdoped regions 242 and 244 and then to the ground terminal GND. AlthoughFIG. 1 only shows one TSV structure 230, more than one TSV may be formedto pass through the substrate 200.

FIGS. 2A-2D show cross-sectional representations of various stages offorming a semiconductor package structure, in accordance with someembodiments of the disclosure. FIG. 2A is an enlarged cross-sectionalrepresentation of a region 300 of the semiconductor package structure100.

As shown in FIG. 2A, the substrate 200 is provided. The materials of thesubstrate 200 are described above, and thus are omitted here. A pair offirst guard ring doped regions 242 are formed in the substrate 200. Apair of second guard ring doped regions 244 are formed adjacent to thefirst guard ring doped regions 242. Note that the guard ring dopedregions 242 and 244 are adjoined to each other.

A conductive type of the first guard ring doped regions 242 is differentfrom that of the second guard ring doped regions 244. In someembodiments, the first guard ring doped regions 242 are n-type guardring doped regions, and second guard ring doped regions 242 are p-typeguard ring doped regions. N-type guard ring doped regions comprisen-type heavily (n⁺) doped region in a n-well region. P-type guard ringdoped regions comprise p-type heavily (P⁺) doped region in a p-wellregion.

The N-type guard ring doped regions 242 are configured to transmit anoise signal with a high frequency, such as in a range from about fewMHz to about several GHz. The P-type guard ring doped regions 244 areconfigured to transmit the noise signal with low frequency, such as isin a range from about few MHz to about several GHz. Because the N-typeguard ring doped regions 242 and P-type guard ring doped regions 244 aresimultaneously formed in the substrate 200, noise signals with a high orlow frequency can be transmitted to the ground GND. Therefore, the noisecan be effectively decreased.

A plurality of well regions 245 are formed adjacent to the second guardring doped regions 244. In some embodiments, when the substrate 200 is ap-type substrate, and the well regions 245 are p-type well regions. Anun-doped region between the second guard ring doped regions 244 and thewell regions 245 is called a native region. The native region is used toincrease resistivity without any dopant. The noise may be reduced byhigher resistivity.

After first guard ring doped regions 242 and second guard ring dopedregions 244 are formed, the IMD layer 250 is formed on the front side203 of the substrate 200. Afterwards, the poly pattern 238 is formed inthe IMD layer 250 and on the front side 203 of the substrate 200. Thepoly pattern 238 is used as an etching stop layer for a subsequentetching process.

Afterwards, a photolithography process and an etching process areperformed to the substrate 200 from the back side 203 of the substrate200 until the poly pattern 238 is exposed. A trench 240 a is therebyformed through the substrate 200.

After the trench 240 a is formed, the insulating layer 232 isconformally formed lining the back side 203 of the substrate 200, and abottom surface and sidewalls of the trench 240 a as shown in FIG. 2B, inaccordance with some embodiments of the disclosure. The insulating layer232 is made of an insulating material, such as oxides or nitrides.

After the insulating layer 232 is formed, an etching back process isperformed to the back side 203 of the substrate 200 to remove theinsulating layer 232 formed on the back side 203 of the substrate 200and on the bottom surface of the trench 240 as shown in FIG. 2C, inaccordance with some embodiments of the disclosure. As a result, thepoly pattern 238 is exposed and a through via 240 b is formed. In someembodiments, the etching back process is a wet etching process or a dryetching process.

After the through via 240 b is formed, a conductive material 234 isfilled into the through via 240 b and on the back side 203 of thesubstrate 200 as shown in FIG. 2D, in accordance with some embodimentsof the disclosure. In some embodiments, the conductive material 234 ismade of copper (Cu), copper alloy, aluminum (Al), aluminum alloys, orcombinations thereof. In some embodiments, the conductive material 234is formed by plating.

Afterwards, a polishing process is performed to remove the excess of theconductive material 234 outside of the through via 240 b. In someembodiments, the polishing process is a chemical mechanical polishing(CMP) process. Therefore, the TSV structure 230 including the insulatinglayer 232 and the conductive material 234 is formed.

After the polishing process, a conductive bump 236 is formed on theconductive material 234. In some embodiments, the conductive bump 236 isa solder bump. In some embodiments, conductive material 234 is made ofconductive materials with low resistivity, such as solder or solderalloy. Exemplary elements included in the solder alloy include Sn, Pb,Ag, Cu, Ni, Bi or combinations thereof.

As shown in FIG. 2D, the conductive material 234 has two terminalsrespectively formed on the front side 201 and back side 203 of thesubstrate 200. One terminal of the conductive material 234 is connectedto the poly pattern 238, and another terminal of the conductive material234 is connected to the conductive bump 236.

It should be noted that the first and the second guard ring dopedregions 242 and 244 are coupled to a ground terminal GND. Therefore, thenoise coupling from the substrate 200 or the TSV structure 230 aretransmitted to the first and the second guard ring doped regions 242 and244 and then to the ground terminal GND. For example, the noise couplingfrom the TSV structure 230 is transmitted to the ground terminal GNDthrough the substrate 200 and the guard ring doped regions 242 and 244,marked by arrow 290 in FIG. 2D.

In some embodiments, the first and second guard ring doped regions 242and 244 have a depth D₁ in a range from about few hundred nm to aboutfew μm. In some embodiments, a ratio (D₁/H₁) of the depth D₁ of theguard ring doped regions to the height H₁ of the through silicon via(TSV) interconnect structure 230 is in a range from 30 μm to about 100μm. If the ratio (D₁/H₁) is too low, less noise is absorbed by secondguard ring doped regions 244. If the ratio (D₁/H₁) is too high, lessnoise is absorbed by second guard ring doped regions 244.

FIG. 3 shows a cross-sectional representation of a semiconductor packagestructure, in accordance with some embodiments of the disclosure. FIG. 3is similar to FIG. 2D, the difference between FIG. 2D and FIG. 3 beingthat a third guard ring doped region 246 is formed adjacent to thesecond guard ring doped region 244 in FIG. 3. In other words, the thirdguard ring doped region 246 is formed between the well region 245 andthe second guard ring doped region 244.

FIG. 4 shows a cross-sectional representation of a semiconductor packagestructure, in accordance with some embodiments of the disclosure. FIG. 3is similar to FIG. 2D, the difference between FIG. 2D and FIG. 4 beingthat a fourth guard ring doped region 248 is formed adjacent to thethird guard ring doped region 246 in FIG. 4. The number of guard ringdoped regions is not limited to two, three or four, and it may beadjusted according to the actual application.

Embodiments for forming a semiconductor package structure are provided.A through silicon via (TSV) interconnect structure is formed in asubstrate. At least two guard ring doped regions are formed in asubstrate and adjacent to the TSV structure. The guard ring dopedregions are coupled to a ground terminal. The two adjacent guard ringdoped regions have different doped regions. The n-type guard ring dopedregion is adjoined to the p-type guard ring doped region. The noisesignals with high frequency or low frequency from the substrate or theTSV structure can be transmitted to a ground GND by using the guard ringdoped regions. Moreover, the semiconductor package structure can beapplied to the TSV technology without additional fabrication steps.

In some embodiments, a semiconductor package structure is provided. Thesemiconductor package structure includes a substrate and the substratehas a front side and a back side. The semiconductor package structureincludes a through silicon via (TSV) interconnect structure formed inthe substrate; and a first guard ring doped region and a second guardring doped region formed in the substrate, and the first guard ringdoped region and the second guard doped region are adjacent to the TSVinterconnect structure.

In some embodiments, a method for forming a semiconductor packagestructure is provided. The method includes providing a substrate and thesubstrate has a front side and a back side. The method also includesforming a first guard ring doped region and a second guard ring dopedregion in the substrate. The method also includes forming a trenchthrough the substrate from a back side of the substrate and conformallyforming an insulating layer lining the back side of the substrate, abottom surface and sidewalls of the trench. The method further includesremoving a portion of the insulating layer on the back side of thesubstrate to form a through via; and forming a conductive material inthe through via, wherein a through silicon via (TSV) interconnectstructure is formed by the insulating layer and the conductive material.

While the invention has been described by way of example and in terms ofthe preferred embodiments, it is to be understood that the invention isnot limited to the disclosed embodiments. On the contrary, it isintended to cover various modifications and similar arrangements (aswould be apparent to those skilled in the art). Therefore, the scope ofthe appended claims should be accorded the broadest interpretation so asto encompass all such modifications and similar arrangements.

What is claimed is:
 1. A method for forming a semiconductor packagestructure, comprising: providing a substrate, wherein the substrate hasa front side and a back side; forming a first guard ring doped regionand a second guard ring doped region in the substrate, wherein the firstguard ring doped region and the second guard ring doped region havedifferent conductive types; forming a trench through the substrate froma back side of the substrate; conformally forming an insulating layerlining the back side of the substrate, a bottom surface and sidewalls ofthe trench; removing a portion of the insulating layer on the back sideof the substrate to form a through via; and forming a conductivematerial in the through via, wherein a through silicon via (TSV)interconnect structure is formed by the insulating layer and theconductive material.
 2. The method as claimed in claim 1, furthercomprising: forming a conductive bump on the back side of the substrateand the conductive material.
 3. The method as claimed in claim 1, beforeforming the trench through the substrate, further comprising: forming apoly pattern on the front side of the substrate.
 4. The method asclaimed in claim 1, further comprising: forming a well region adjacentto the second guard ring doped region.
 5. The method as claimed in claim1, further comprising: coupling the first guard ring doped region andthe second guard ring doped region to a ground terminal.
 6. The methodas claimed in claim 1, further comprising: forming a third guard ringdoped region adjacent to the second guard ring doped region; and forminga fourth guard ring doped region adjacent to the third guard ring dopedregion, wherein a conductive type of the third guard ring doped regionis different from that of the fourth guard ring doped region.
 7. Themethod as claimed in claim 6, further comprising: coupling the thirdguard ring doped region and the fourth guard ring doped region to aground terminal.
 8. The method as claimed in claim 1, wherein formingthe first guard ring doped region and the second guard ring doped regionin the substrate comprises: forming a n-type heavily (n+) doped regionin the n-well region; and forming a p-type heavily (p+) doped region inthe p-well region.
 9. The method as claimed in claim 1, wherein thefirst guard ring doped region and the second guard ring doped regionadjacent to the through silicon via (TSV) interconnect structure.
 10. Amethod for forming a semiconductor package structure, comprising:providing a substrate, wherein the substrate has a front side and a backside; forming a first guard ring doped region and a second guard ringdoped region in the substrate; forming a trench through the substratefrom a back side of the substrate; conformally forming an insulatinglayer lining the back side of the substrate, a bottom surface andsidewalls of the trench; removing a portion of the insulating layer onthe back side of the substrate to form a through via; and forming aconductive material in the through via, wherein a through silicon via(TSV) interconnect structure is formed by the insulating layer and theconductive material, wherein the first guard ring doped region and asecond guard ring doped region are adjacent to the through silicon via(TSV) interconnect structure.
 11. The method as claimed in claim 10,further comprising: forming a conductive bump on the back side of thesubstrate and the conductive material.
 12. The method as claimed inclaim 10, before forming the trench through the substrate, furthercomprising: forming a poly pattern on the front side of the substrate.13. The method as claimed in claim 10, further comprising: forming awell region adjacent to the second guard ring doped region.
 14. Themethod as claimed in claim 10, further comprising: coupling the firstguard ring doped region and the second guard ring doped region to aground terminal.
 15. The method as claimed in claim 10, furthercomprising: forming a third guard ring doped region adjacent to thesecond guard ring doped region; and forming a fourth guard ring dopedregion adjacent to the third guard ring doped region, wherein aconductive type of the third guard ring doped region is different fromthat of the fourth guard ring doped region.
 16. The method as claimed inclaim 15, further comprising: coupling the third guard ring doped regionand the fourth guard ring doped region to a ground terminal.
 17. Themethod as claimed in claim 10, wherein forming the first guard ringdoped region and the second guard ring doped region in the substratecomprises: forming a n-type heavily (n+) doped region in the n-wellregion; and forming a p-type heavily (p+) doped region in the p-wellregion.
 18. The method as claimed in claim 10, wherein the first guardring doped region and the second guard ring doped region have differentconductive types.